What it says is that the client certificate must validate according to the complete certificate chain. In broader terms it forces the caller to use the certificate that is 'validatable' on the service side. This means the following:

The certificate must be present at the time of request generation (client side)

The certificate must be valid according to expiration period and certificate generation (checking done on server side)

The certificate chain (issuing CAs path) must be valid (certificateValidationMode="ChainTrust")

The certificate must not be obsolete and/or revoked (revocationMode="Online")

Other authentication options of certificateValidationMode and revocationMode include:

certificateValidationMode can take a velue of ChainTrust, PeerTrust, ChainOrPeerTrust, None or Custom. None means that no certificate checking is done, Custom allows one to plug in a custom X509CertificateValidator (new, System.IdentityModel.Selectors namespace), PeerTrust forces a public key of the client certificate to be present in the 'Trusted People' certificate store on the service side and ChainTrust requests that the client cert can be validated against the root certificates on the server side. ChainOrPeerTrust just executes the OR operator on the last two.Remark:PeerTrust and ChainOrPeerTrust are also subjected to another attribute called trustedStoreLocation. If peer trust is demanded, one can specify where the public keys are present, meaning either in LocalMachine or CurrentUser store.

revocationMode takes the following value list: None, Online or Cached. None is saying that CRL (Certificate Revocation List) is not checked. Online demands that service checks (at every request) whether the certificate is still valid and thus not revoked. Offline says that the certificate should only be checked against the cached CRL.Remark:Online does not mean that CRL will be downloaded from the CA CRL endpoint at every request. It means it will check a local copy of it at every request. Every CRL has a validity period, when it expires, it is downloaded again.

The <metadataPublishing> element is there just to allow WSDL/MetadataExchange endpoints to exist. It also allows the familiar service HTML page to pop up if you hit the endpoint (courtesy of enableHelpPage="true").

Another remark:Current February 2006 WCF CTP bits do not reflect the naming used in this post. For example revocationMode="Cached" was renamed from revocationMode=Offline", but don't be afraid of using it, nevertheless.

Having an option is always a good thing, right? But there comes a time when we all have to face the truth of the free (economic) world. There are things that just do not fit in common line-of-though agenda.

Windows is free to the OEMs. In fact, not only is it free, but Microsoft, in effect, pays them to take it. Regardless of the cost, Windows is a logical choice, and a straight pass. Dell (Nasdaq: DELL) pays about $80 for it and typically charges about $80 for it. There is rarely much of a mark up. If Microsoft were to lower its price that lowered price would be reflected in virtually all desktop hardware immediately.

Microsoft provides a number of services which include development support, service support, marketing support, technicians, classes, databases and support materials, and it picks up a lot of the service load as well. In addition, it provides marketing co-op dollars, incentives for early adoption of new products, and ensures a somewhat level playing field (which could be good or bad) for the vendors.

This is the world we all live in. Market share is made by a conglomerate of superiorities. Not necessarily just technical ones. We do need to acknowledge that sometimes market can be gained by offering better business environment for the complete food chain. One needs to respect the box movers too, they need those extra dollars. They need the extra revenue.

Now, here's the question. What if RedHat/Apple/Ubuntu had Microsoft's position? What would happen then?

Short term? Lower prices - better quality of life.

Long term? The same thing.

If Apple had an opportunity to excell at Microsoft's position, I bet they would exercise it! Actually, they are doing it already.